A recent article noted that it may be possible to accurately predict which way a penalty-shot kicker in soccer will direct his shot.¹The study finds that certain types of body language by a soccer player called tells can be accurately read to predict whether the ball will go left or right. For a given body movement leading up to the kick, the question is whether there is strong evidence that the proportion of kicks that go right is significantly different from one half.

What are the null and alternative hypotheses in this situation?